U.S. patent application number 12/528651 was filed with the patent office on 2010-03-11 for x-ray apparatus.
Invention is credited to Hideki Fujii.
Application Number | 20100061507 12/528651 |
Document ID | / |
Family ID | 39807884 |
Filed Date | 2010-03-11 |
United States Patent
Application |
20100061507 |
Kind Code |
A1 |
Fujii; Hideki |
March 11, 2010 |
X-RAY APPARATUS
Abstract
An X-ray apparatus according to this invention includes an
X-raying condition fixing controller for carrying out controls to
cause an X-ray emission from an X-ray tube on X-raying conditions
effective when an X-ray emission is stopped by the automatic
exposure controller, and turning off automatic exposure control by
the automatic exposure controller. Thus, the automatic exposure
control is carried out only at the time of starting radiography,
and a subsequent sequential shooting can be carried out in the
state of X-raying conditions at that time being locked and the
automatic exposure control being turned off. When X-raying a new
site to be imaged after a current site to be imaged, driving of a
top board is detected during the sequential shooting, and the
automatic exposure control can be carried out only at the time of
starting radiography for the new site to be imaged, and a
subsequent sequential shooting can be carried out in the state of
locking to the X-raying conditions effective at that time, with the
automatic exposure control turned off. As a result, a proper
automatic exposure control can be carried out without setting a
radiographic collection mode.
Inventors: |
Fujii; Hideki; (Kyoto,
JP) |
Correspondence
Address: |
Cheng Law Group, PLLC
1100 17th Street, N.W., Suite 503
Washington
DC
20036
US
|
Family ID: |
39807884 |
Appl. No.: |
12/528651 |
Filed: |
March 1, 2007 |
PCT Filed: |
March 1, 2007 |
PCT NO: |
PCT/JP2007/053896 |
371 Date: |
August 26, 2009 |
Current U.S.
Class: |
378/28 |
Current CPC
Class: |
A61B 6/542 20130101;
A61B 6/5241 20130101; A61B 6/469 20130101; A61B 6/481 20130101;
A61B 6/487 20130101; A61B 6/00 20130101 |
Class at
Publication: |
378/28 |
International
Class: |
A61B 6/00 20060101
A61B006/00; H05G 1/38 20060101 H05G001/38 |
Claims
1. An X-ray apparatus for X-raying a subject, comprising (A) a top
board for supporting, or contactable by, the subject; (B) an X-ray
emitting device for emitting X rays toward the subject on the top
board; (C) an X-ray detecting device opposed to the X-ray emitting
device across the top board for detecting X rays emitted from the
X-ray emitting device and transmitted through the subject; (D) a
storage device for storing X-raying conditions indicating
conditions of X-ray emission from the X-ray emitting device; (E) a
radiography start instruction input device for receiving X-ray
radiography start inputs; (F) a drive instruction input device for
receiving instruction inputs for driving at least one of the X-ray
emitting device and the X-ray detecting device, and the top board;
(G) a drive control device for performing drive control of at least
one of the X-ray emitting device and the X-ray detecting device,
and the top board, based on an instruction from the drive
instruction input device; (H) an input detecting device for
detecting a start instruction from the radiography start
instruction input device or a drive instruction from the drive
instruction input device during a sequential shooting; (I) an
automatic exposure control device for starting, based on an input
detection by the input detecting device, an X-ray emission from the
X-ray emitting device on X-raying conditions read from the storage
device, and for stopping the X-ray emission from the X-ray emitting
device when an amount of transmitted X rays detected by the X-ray
detecting device reaches a predetermined value; and (J) an X-raying
condition fixing control device for carrying out controls to cause
an X-ray emission from the X-ray emitting device on X-raying
conditions effective when the X-ray emission is stopped by the
automatic exposure control device, and turning off the automatic
exposure control by the automatic exposure control device, until a
next input is detected by the input detecting device.
2. The X-ray apparatus according to claim 1, wherein the X-ray
emitting device is an X-ray tube; the X-raying conditions include a
tube voltage value of the X-ray tube, a tube current value of the
X-ray tube and an X-ray emission time value of the X-ray tube; the
automatic exposure control device has an actual radiographing time
measuring device for measuring an actual radiographing time after
starting the X-ray emission from the X-ray emitting device on the
X-raying conditions read from the storage device, based on an input
detection by the input detecting device, until the amount of
transmitted X rays detected by the X-ray detecting device reaches
the predetermined value; and the X-raying condition fixing control
device, until a next input is detected by the input detecting
device, fixes the actual radiographing time measured by the actual
radiographing time measuring device as X-ray emission time on the
X-raying conditions, and turns off the automatic exposure control
by the automatic exposure control device.
3. The X-ray apparatus according to claim 2, wherein the storage
device stores X-raying conditions indicating conditions of X-ray
emission from the X-ray emitting device, for each site to be
imaged.
Description
TECHNICAL FIELD
[0001] This invention relates to an X-ray apparatus for emitting X
rays from an X-ray emitting device to a radiographic subject to
acquire X-ray fluoroscopic images of the radiographic subject, and
more particularly to a technique for carrying out a proper
automatic exposure control without setting a radiographic
acquisition mode.
BACKGROUND ART
[0002] Conventionally, X-ray radiography with an X-ray apparatus is
carried out based on X-raying conditions including a tube voltage,
a tube current and an emission time of an X-ray tube. In certain
cases, an automatic exposure control is carried out to end (cut
off) the emission of X rays from the X-ray tube when X rays emitted
from the X-ray tube and transmitted through a subject have reached
a predetermined amount, to keep the contrast of X-ray fluoroscopic
images in an optimal state. That is, the automatic exposure control
aims at keeping film density constant through an automatic control
of exposure time. Specifically, the control is intended to obtain a
desired film density by converting an amount of X rays transmitted
through a subject into electric signals, and cutting off X rays
when this amount of electricity reaches a fixed value (see Patent
Document 1).
[0003] In certain cases, a flat panel X-ray detector (hereinafter
abbreviated as "FPD") is provided in place of the film in the X-ray
apparatus noted above. The FPD has a sensitive film laminated on a
substrate, detects X rays incident on the sensitive film, converts
the detected X rays into electric charges, and stores the electric
charges in capacitors arranged in a two-dimensional array. The
stored electric charges are read by turning on switching elements,
and are fed as X-ray detection signals into an image processor
disposed at a subsequent stage. Then, the image processor provides
X-ray fluoroscopic images based on the X-ray detection signals.
[0004] Further, an X-ray apparatus with this FPD may have a
sequential shooting function as well as the above-noted automatic
exposure control function. That is, the above-noted automatic
exposure control is carried out at each shooting time of the
sequential shooting. Specifically, when radiography (X-ray
emission) is started and an amount of transmitted X rays reaches a
predetermined value, the X-ray emission is stopped by the
above-noted automatic exposure control to complete the current
radiography. The automatic exposure control is carried out for a
next radiography also. Thus, a plurality of consecutive X-ray
fluoroscopic images are acquired under automatic exposure control
operating constantly (at each emission).
[0005] Before starting a sequential shooting radiography, the
operator (e.g. an X-ray radiographer) needs to set a radiographic
collection mode to this X-ray apparatus, such as a subtraction
mode, a mode of moving a radiographic system or a fluoroscopic
table, or, conversely, a non-moving mode, in order to determine
whether to carry out the sequential shooting radiography in a state
of locking (fixing) X-raying conditions or in a state of automatic
exposure control. The subtraction mode is, for example, for
acquiring subtraction images (difference images) based on
differences between mask images (images before injection of a
contrast medium) and live images (images after injection of the
contrast medium). The mode of moving a radiographic system or a
fluoroscopic table is, for example, for radiographing a plurality
of sites to be imaged of a subject successively by moving the
radiographic system or the fluoroscopic table. The non-moving mode
is, for example, for radiographing a single site to be imaged of a
subject without moving the radiographic system or the fluoroscopic
table.
[0006] [Patent Document 1]
[0007] Unexamined Patent Publication No. No. 2000-173795 (page 2,
FIG. 11)
DISCLOSURE OF THE INVENTION
Problems to be Solved by the Invention
[0008] However, the conventional X-ray apparatus have the following
problems. In a sequential shooting for acquiring subtraction
images, forgetting to set the subtraction mode will result in a
problem that X-raying conditions are not locked, but the automatic
exposure control is constantly operational to conduct radiography
on various X-raying conditions, thereby failing to obtain proper
subtraction images (difference images). The same will occur with an
X-ray apparatus combined with a digital processing device without a
function to notify setting of the above mode. Even if the
subtraction mode is set, when a plurality of sites are X-rayed as
in leg DSA (digital subtraction angiography), and when the
automatic exposure control is carried out once at the time of first
radiography for the first site to be imaged, the X-raying
conditions at that time will be locked. This results in a problem
that proper subtraction images (difference images) cannot be
obtained since radiography is conducted on the X-raying conditions
as they are even if the radiographic system or the fluoroscopic
table is moved to make a shift to other sites to be imaged.
[0009] Supposing the above "non-moving mode" is set and the
automatic exposure control function is constantly on when live
images are acquired through sequential shooting without moving the
radiographic system and fluoroscopic table, there arises a problem
that, under the influence of a contrast medium such as barium, all
the frames in a series of live images cannot obtain a uniform
luminance level.
[0010] That is, there is a problem that a proper automatic exposure
control cannot necessarily be carried out only with setting of the
radiographic acquisition mode.
[0011] However, if X-raying conditions are locked unconditionally,
when a plurality of sites are X-rayed, it will become impossible to
turn on the automatic exposure control function for each site to be
imaged, resulting in a problem that proper radiographic images
cannot be obtained.
[0012] This invention has been made having regard to the state of
the art noted above, and its object is to provide an X-ray
apparatus which can carry out proper automatic exposure control
without setting a radiographic acquisition mode.
Means for Solving the Problems
[0013] To fulfill the above object, this invention provides the
following construction.
[0014] An X-ray apparatus according to this invention is an X-ray
apparatus for X-raying a subject, comprising (A) a top board for
supporting, or contactable by, the subject; (B) an X-ray emitting
device for emitting X rays toward the subject on the top board; (C)
an X-ray detecting device opposed to the X-ray emitting device
across the top board for detecting X rays emitted from the X-ray
emitting device and transmitted through the subject; (D) a storage
device for storing X-raying conditions indicating conditions of
X-ray emission from the X-ray emitting device; (E) a radiography
start instruction input device for receiving X-ray radiography
start inputs; (F) a drive instruction input device for receiving
instruction inputs for driving at least one of the X-ray emitting
device and the X-ray detecting device, and the top board; (G) a
drive control device for performing drive control of at least one
of the X-ray emitting device and the X-ray detecting device, and
the top board, based on an instruction from the drive instruction
input device; (H) an input detecting device for detecting a start
instruction from the radiography start instruction input device or
a drive instruction from the drive instruction input device during
a sequential shooting; (I) an automatic exposure control device for
starting, based on an input detection by the input detecting
device, an X-ray emission from the X-ray emitting device on
X-raying conditions read from the storage device, and for stopping
the X-ray emission from the X-ray emitting device when an amount of
transmitted X rays detected by the X-ray detecting device reaches a
predetermined value; and (J) an X-raying condition fixing control
device for carrying out controls to cause an X-ray emission from
the X-ray emitting device on X-raying conditions effective when the
X-ray emission is stopped by the automatic exposure control device,
and turning off the automatic exposure control by the automatic
exposure control device, until a next input is detected by the
input detecting device.
[0015] According to the X-ray apparatus of this invention, the
X-ray emitting device emits X rays toward the patient on the top
board. The X-ray detecting device is opposed to the X-ray emitting
device across the top board for detecting X rays emitted from the
X-ray emitting device and transmitted through the subject. The
storage device stores X-raying conditions indicating conditions of
X-ray emission from the X-ray emitting device. The radiography
start instruction input device receives X-ray radiography start
inputs. The drive instruction input device receives instruction
inputs for driving at least one of the X-ray emitting device and
the X-ray detecting device, and the top board. The drive control
device performs drive control of at least one of the X-ray emitting
device and the X-ray detecting device, and the top board, based on
an instruction from the drive instruction input device. The input
detecting device detects a start instruction from the radiography
start instruction input device or a drive instruction from the
drive instruction input device during a sequential shooting. The
automatic exposure control device starts, based on an input
detection by the input detecting device, an X-ray emission from the
X-ray emitting device on X-raying conditions read from the storage
device, and stops the X-ray emission from the X-ray emitting device
when an amount of transmitted X rays detected by the X-ray
detecting device reaches a predetermined value. The X-raying
condition fixing control device carries out controls to cause an
X-ray emission from the X-ray emitting device on X-raying
conditions effective when the X-ray emission is stopped by the
automatic exposure control device, and turns off the automatic
exposure control by the automatic exposure control device, until a
next input is detected by the input detecting device.
[0016] Thus, the automatic exposure control can be carried out only
at the time of starting radiography, and a subsequent sequential
shooting can be carried out in the state of X-raying conditions at
that time being locked and the automatic exposure control being
turned off. Supposing an attempt is made to carry out X-ray
radiography of a new site to be imaged in place of a current site
to be imaged, since a drive instruction from the drive instruction
input device (i.e. an instruction to drive at least one of the
X-ray emitting device and the X-ray detecting device, and the top
board) is detected during the sequential shooting, the automatic
exposure control can be carried out only at the time of starting
radiography for the new site to be imaged by this drive
instruction, and a subsequent sequential shooting can be carried
out in the state of being locked to the X-raying conditions
effective at that time, with the automatic exposure control turned
off. As a result, a proper automatic exposure control can be
carried out without setting a radiographic collection mode such as
a subtraction mode, a mode of moving a radiographic system or a
fluoroscopic table, or a non-moving mode.
[0017] At a time of sequential shooting for acquiring subtraction
images, for example, there is no need for setting a subtraction
mode, and a subsequent sequential shooting can be carried out in a
state of being locked to X-raying conditions acquired from the
automatic exposure control used only at the time of staring
radiography, and with the automatic exposure control turned off.
This allows a mask image and live images to be obtained on the same
X-raying conditions, thereby to obtain proper subtraction images
(difference images). Also in the case of an X-ray apparatus
combined with a digital processing device without a function of
notifying setting of the above mode, proper subtraction images
(difference images) can be obtained similarly. When X-ray
radiography is carried out for a plurality of sites as in DSA
(digital subtraction angiography), the automatic exposure control
is carried out once at the time of first radiography for the first
site to be imaged, the X-raying conditions at that time can be
locked, and X-ray radiography can be carried out on the locked
X-raying conditions until a change is made in the sites to be
imaged. When a shift is made to a different site to be imaged, by
moving the radiographic system or the fluoroscopic table, the
automatic exposure control is carried out once at the time of first
radiography for the different site to be imaged, and the X-raying
conditions at that time can be locked for X-ray radiography. Thus,
proper subtraction images (difference images) can be obtained also
when X-ray radiography is carried out for a plurality of sites.
[0018] Also when a sequential shooting is carried out to acquire
live images without moving the radiographic system and fluoroscopic
table, there is no need for setting the above-noted "non-moving
mode" or the like, and a subsequent sequential shooting can be
carried out in a state of being locked to X-raying conditions
acquired from the automatic exposure control used only at the time
of staring radiography, and with the automatic exposure control
turned off. This realizes a uniform luminance for all frames of a
series of live images, without being influenced by a contrast
medium such as barium.
[0019] That is, a proper automatic exposure control can be carried
out without setting the radiographic acquisition mode.
[0020] X-raying conditions are never locked unconditionally. When
X-ray radiography is carried out for a plurality of sites, the
automatic exposure control function can be turned on only at the
time of starting radiography for each site to be imaged, thereby to
obtain proper radiographic images.
[0021] Preferably, the X-ray emitting device is an X-ray tube; the
X-raying conditions include a tube voltage value of the X-ray tube,
a tube current value of the X-ray tube and an X-ray emission time
value of the X-ray tube; the automatic exposure control device has
an actual radiographing time measuring device for measuring an
actual radiographing time after starting the X-ray emission from
the X-ray emitting device on the X-raying conditions read from the
storage device, based on an input detection by the input detecting
device, until the amount of transmitted X rays detected by the
X-ray detecting device reaches the predetermined value; and the
X-raying condition fixing control device, until a next input is
detected by the input detecting device, fixes the actual
radiographing time measured by the actual radiographing time
measuring device as X-ray emission time on the X-raying conditions,
and turns off the automatic exposure control by the automatic
exposure control device.
[0022] With this construction, the automatic exposure control can
be carried out only at the time of starting radiography, and a
subsequent sequential shooting can be carried out in the state of
X-raying conditions at that time (X-ray emission time of the X-ray
tube acquired by the automatic exposure control) being locked and
the automatic exposure control being turned off. Supposing an
attempt is made to carry out X-ray radiography of a new site to be
imaged in place of a current site to be imaged, since a drive
instruction from the drive instruction input device (i.e. an
instruction to drive at least one of the X-ray emitting device and
X-ray detecting device, and the top board) is detected during the
sequential shooting, the automatic exposure control can be carried
out only at the time of starting radiography for the new site to be
imaged by this drive instruction, and a subsequent sequential
shooting can be carried out in the state of being locked to the
X-raying conditions effective at that time (X-ray emission time of
the X-ray tube acquired from the automatic exposure control), with
the automatic exposure control turned off. As a result, a proper
automatic exposure control can be carried out without setting a
radiographic collection mode such as a subtraction mode, a mode of
moving a radiographic system or a fluoroscopic table, or a
non-moving mode.
[0023] Preferably, the storage device stores X-raying conditions
indicating conditions of X-ray emission from the X-ray emitting
device, for each site to be imaged. In this case, since X-raying
conditions for various sites to be imaged are stored, various sites
to be imaged can be X-rayed conveniently.
Effects of the Invention
[0024] With the X-ray apparatus according to this invention, the
automatic exposure control can be carried out only at the time of
starting radiography, and a subsequent sequential shooting can be
carried out in the state of X-raying conditions at that time being
locked and the automatic exposure control being turned off.
Supposing an attempt is made to carry out X-ray radiography of a
new site to be imaged in place of a current site to be imaged,
since a drive instruction from the drive instruction input device
(i.e. an instruction to drive at least one of the X-ray emitting
device and the X-ray detecting device, and the top board) are
detected during the sequential shooting, the automatic exposure
control can be carried out only at the time of starting radiography
for the new site to be imaged by this drive instruction, and a
subsequent sequential shooting can be carried out in the state of
being locked to the X-raying conditions effective at that time,
with the automatic exposure control turned off. As a result, a
proper automatic exposure control can be carried out without
setting a radiographic acquisition mode such as a subtraction mode,
a mode of moving a radiographic system or a fluoroscopic table, or
a non-moving mode.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] FIG. 1 is a block diagram showing an overall construction of
an X-ray apparatus;
[0026] FIG. 2 is a block diagram showing a construction of an
automatic exposure controller in Embodiment 1;
[0027] FIG. 3 is a view showing part of a display screen of a
display unit;
[0028] FIG. 4 is a flow chart showing a flow of operation in
radiographing a procedure of pursuing blood flows from the lower
abdomen to a leg with the X-ray apparatus in Embodiment 1; and
[0029] FIG. 5 is a flow chart showing the flow of operation in
radiographing the procedure of pursuing blood flows from the lower
abdomen to the leg with the X-ray apparatus in Embodiment 1.
DESCRIPTION OF REFERENCES
[0030] 1 . . . top board
[0031] 2 . . . X-ray tube (X-ray emitting device)
[0032] 3 . . . FPD
[0033] 4 . . . radiography controller
[0034] 5 . . . emission controller
[0035] 6 . . . input unit
[0036] 7 . . . display unit
[0037] 8 . . . hand switch (radiography start instruction input
device)
[0038] 9 . . . top board drive switch (drive instruction input
device)
[0039] 10 . . . top board drive controller (drive control
device)
[0040] 13 . . . automatic exposure detector (X-ray detecting
device)
[0041] 14 . . . storage unit (storage device)
[0042] 15 . . . input detector (input detecting device)
[0043] 16 . . . automatic exposure controller (automatic exposure
control device)
[0044] 17 . . . X-raying condition fixing controller (X-raying
condition fixing control device)
[0045] 18 . . . timer (actual exposure time measuring device)
BEST MODE FOR CARRYING OUT THE INVENTION
[0046] An automatic exposure control device, based on an input
detection by an input detecting device, starts an X-ray emission
from an X-ray emitting device on X-raying conditions read from a
storage device, and stops the X-ray emission from the X-ray
emitting device when an amount of transmitted X rays detected by an
X-ray detecting device reaches a predetermined value. An X-raying
condition fixing control device, until a next input is detected by
the input detecting device, controls the X-ray emission of the
X-ray emitting device to be carried out on the X-raying conditions
effective when the X-ray emission is stopped by the automatic
exposure control device, and turns off the automatic exposure
control by the automatic exposure control device. Thus, the
automatic exposure control can be carried out only at a time of
starting radiography, and a subsequent sequential shooting can be
carried out in a state of the X-raying conditions at that time
being locked and the automatic exposure control being turned off.
As a result, therefore, the object has been fulfilled of providing
an X-ray apparatus which can carry out proper automatic exposure
control without setting a radiographic acquisition mode such as a
subtraction mode, a mode of moving a radiographic system or a
fluoroscopic table, or a non-moving mode.
Embodiment 1
[0047] Embodiment 1 of this invention will be described hereinafter
with reference to the drawings. FIG. 1 is a block diagram showing
an overall construction of an X-ray apparatus. FIG. 2 is a block
diagram showing a construction of an automatic exposure controller
in Embodiment 1. FIG. 3 is a view showing part of a display screen
of a display unit.
[0048] The overall construction of the X-ray apparatus will be
described using FIG. 1. As shown in FIG. 1, the X-ray apparatus
includes a top board 1 for supporting a subject (patient) M, an
X-ray tube 2 for emitting X rays toward the subject M on the top
board 1, an FPD 3 opposed to the X-ray tube 2 across the top board
1 for detecting X rays emitted from the X-ray tube 2 and
transmitted through the subject M, a radiography controller 4 for
performing various controls relating to X-ray radiography, an
emission controller 5 for controlling the X-ray tube 2 based on the
controls from this radiography controller 4, an input unit 6 for
inputting X-raying conditions and the like indicating sites to be
imaged and conditions of X-ray emission from the X-ray tube 2, a
display unit 7 for displaying the X-raying conditions and the like,
a hand switch (emission switch) 8 for instructing a start of X-ray
radiography (start of X-ray emission), a top board drive switch 9
for instructing driving of the top board 1, a top board drive
controller 10 for performing drive control longitudinally of the
top board 1 based on the instruction from this top board drive
switch 9, an analog-to-digital converter 11 for digitizing and
fetching X-ray detection signals from the FPD 3, and an image
processor 12 for performing various processes (e.g. processes for
creating X-ray fluoroscopic images) based on the X-ray detection
signals outputted from the analog-to-digital converter 11.
[0049] The hand switch 8 instructs a start of X-ray emission when a
button is depressed. The top board drive switch 9 includes a
forward switch for advancing the top board 1 in one longitudinal
direction thereof, and a backward switch for returning it in the
opposite direction.
[0050] That is, a start of X-ray emission is instructed when the
hand switch 8 is operated (e.g. the button is depressed) by the
operator (e.g. an X-ray radiographer). The radiography controller 4
generates a high voltage in the emission controller 5 based on the
X-raying conditions according to the sites to be imaged inputted
from the input unit 6, for causing the X-ray tube 2 to emit X rays.
The X-ray radiography is terminated when the hand switch 8 is
released (i.e. the depression of the button is stopped). In a state
of continuing operation of the hand switch 8 (continuing depression
of the bottom), a sequential shooting is carried out to acquire a
plurality of X-ray fluoroscopic images consecutively.
[0051] An automatic exposure detector 13 is disposed at outer edges
on the X-ray incidence plane of the FPD 3 for detecting X rays
emitted from the X-ray tube 2 and transmitted through the subject
M.
[0052] The automatic exposure detector 13 is constructed, for
example, of a fluorescent panel (not shown) which emits light
corresponding to the intensity of X rays emitted from the X-ray
tube 2 and transmitted through the subject M, and a photomultiplier
tube (not shown) which converts the light emitted from this
fluorescent panel into electric signals. That is, the automatic
exposure detector 13 is constructed to output to the radiography
controller 4 electric signals corresponding to an amount of X rays
transmitted through the subject M.
[0053] Although the automatic exposure detector 13 is disposed at
the outer edges on the X-ray incidence plane of the FPD 3 in
Embodiment 1, it may be disposed only in predetermined locations
(e.g. three locations) on the X-ray incidence plane of the FPD 3. A
detector such as a photo pickup which detects incident X rays may
be employed, or various detectors which can detect an amount of
incident X rays may be employed.
[0054] The X-ray tube 2 noted above corresponds to the X-ray
emitting device in this invention. The automatic exposure detector
13 noted above corresponds to the X-ray detecting device in this
invention. The hand switch 8 noted above corresponds to the
radiography start instruction input device in this invention. The
top board drive switch 9 noted above corresponds to the drive
instruction input device in this invention. The top board drive
controller 10 noted above corresponds to the drive control device
in this invention.
[0055] Next, the radiography controller 4, as shown in FIG. 1,
includes a storage unit 14 for storing X-raying conditions
indicating conditions of X-ray emission from the X-ray tube 2, an
input detector 15 for detecting a start instruction from the hand
switch 8 or a drive instruction from the top board drive switch 9
during a sequential shooting, an automatic exposure controller
(AEC) 16 for carrying out automatic exposure control to maintain
the luminance (density) of X-ray fluoroscopic images detected by
the FPD 3 in a proper state through controls for starting, based on
an input detection by the input detector 15, X-ray emission from
the X-ray tube 2 on the X-raying conditions read from the storage
unit 14, and for causing the emission controller 5 to stop the
X-ray emission when the electric signals from the automatic
exposure detector 13 reach a predetermined value (i.e. when the
amount of transmitted X rays detected by the automatic exposure
detector 13 reaches a predetermined value), and an X-raying
condition fixing controller 17 for carrying out controls to cause
an X-ray emission from the X-ray tube 2 on X-raying conditions
effective when the X-ray emission is stopped by the automatic
exposure controller 16, and turning off the automatic exposure
control by the automatic exposure controller 16, until a next input
is detected by the input detector 15.
[0056] The automatic exposure controller 16 has a timer 18 which,
based on an input detection by the input detector 15 (detection of
an X-ray emission start instruction from the hand switch 8 or
detection of a top board drive instruction from the top board drive
switch 9), measures an actual radiographing time from start of an
X-ray emission from the X-ray tube 2 on the X-raying conditions
read from the storage unit 14 until the amount of transmitted X
rays detected by the automatic exposure detector 13 reaches the
predetermined value.
[0057] Objects to be imaged (sites to be imaged), in a broad
classification, include the head, chest, abdomen and legs, for
example. In subdivided terms, the legs include the thighs, calves,
and tips of the feet, for example. A radiographing direction may be
frontal or sideways, for example. The X-raying conditions include a
tube voltage, a tube current (tube current time product) and an
X-ray emission upper limit time for determining X rays emitted from
the X-ray tube 2, for example. The X-raying conditions
corresponding to an object to be imaged, in the case of the front
of the lower abdomen, for example, may be a tube voltage, a tube
current (tube current time product) and an X-ray emission upper
limit time corresponding to the front of the lower abdomen.
Further, the X-ray emission upper limit time is a maximum X-ray
emitting time from start of an X-ray emission. 0
[0058] The automatic exposure controller 16, as shown in FIG. 2,
includes an integrator 21, a comparator/detector 22 and a reference
voltage memory 23. The integrator 21 carries out time integration
of the electric signals outputted from the automatic exposure
detector 13, and outputs a voltage signal indicating a total amount
of transmitted X rays to the comparator/detector 22. The
comparator/detector 22 compares the voltage signal outputted from
the integrator 21 and a reference voltage stored in the reference
voltage memory 23 and indicating a predetermined amount of
transmitted X rays corresponding to an object to be imaged (site to
be imaged), and outputs an X-ray emission ending signal to the
emission controller 5 when the two voltage values are in agreement,
that is when the voltage signal outputted from the integrator 21
reaches the reference voltage. The reference voltages stored in the
reference voltage memory 23 and corresponding to the objects to be
imaged are inputted and set beforehand by the input unit 6.
[0059] The storage unit 14 noted above corresponds to the storage
device in this invention. The input detector 15 noted above
corresponds to the input detecting device in this invention. The
automatic exposure controller 16 noted above corresponds to the
automatic exposure control device in this invention. The X-raying
condition fixing controller 17 noted above corresponds to the
X-raying condition fixing control device in this invention. The
timer 18 noted above corresponds to the actual exposure time
measuring device in this invention.
[0060] The radiography controller 4 is constructed, upon receipt of
a site to be imaged and a radiographing direction from the input
unit 6, to read the X-raying conditions corresponding thereto from
the storage unit 14, and output X-raying condition signals
indicating the X-raying conditions (tube voltage, tube current and
X-ray emission upper limit time) to the emission controller 5.
Further, as shown in FIG. 3, the display unit 7 is constructed to
display these site to be imaged, radiographing direction and
X-raying conditions.
[0061] The radiography controller 4, upon receipt of an X-ray
radiography start instruction (an X-ray emission starting signal
indicating that an instruction for starting X-ray radiography has
been given) from the hand switch 8, carries out a control for
starting X-ray emission by outputting an X-ray emission starting
signal to the emission controller 5.
[0062] The radiography controller 4 has a CPU (not shown) for
performing various arithmetic control processes. Programs and data
to be executed by this CPU (not shown) are stored beforehand in the
storage unit 14. Various functions of this radiography controller 4
are realized by the CPU executing predetermined programs stored in
the storage unit 14.
[0063] Next, as shown in FIG. 1, the emission controller 5 includes
a tube voltage controller 24, a filament current controller 25 and
a radiographing time controller 26. The tube voltage controller 24
converts a commercial supply voltage into a high voltage, and
controls the voltage of the anode and cathode of the X-ray tube 2.
The filament current controller 25 heats the filament (cathode) of
the X-ray tube 2, and by controlling this, controls a current
flowing to the X-ray tube 2. Specifically, the input of the
X-raying condition signals outputted from the radiography
controller 4 sets a voltage to be outputted from the tube voltage
controller 24 and a current flowing to the X-ray tube 2 under
control of the filament current controller 25. The radiographing
time controller 26 controls the X-ray emission time of the X-ray
tube 2 to be, at a maximum, up to the X-ray emission upper limit
time at the time of automatic exposure control (when the automatic
exposure control is on), and when the automatic exposure control is
off, controls to stop the X-ray emission from the X-ray tube 2 at a
time when the automatic exposure controller 16 stops the X-ray
emission.
[0064] Now, operation in radiographing a procedure, for example, of
pursuing blood flows from the lower abdomen to a leg with this
X-ray apparatus will be described in detail using also FIGS. 4 and
5. FIGS. 4 and 5 are flow charts showing a flow of operation in
radiographing a procedure of pursuing blood flows from the lower
abdomen to a leg with the X-ray apparatus in Embodiment 1
[0065] [Step S1] Select Site to Be Imaged
[0066] As shown in FIG. 4, the "lower abdomen" is selected as a
site to be imaged. Specifically, the operator, using the input unit
6, selects and inputs the site to be imaged to be the "lower
abdomen" on the display screen shown in FIG. 3. The operator
selects also the radiographing direction to be "frontal", using the
input unit 6.
[0067] [Step S2] Read X-Raying Conditions Corresponding to Site to
Be Imaged "Lower Abdomen"
[0068] When the site to be imaged "lower abdomen" and the
radiographing direction "frontal" have been selected in step S1, in
step S2 the radiography controller 4 reads X-raying conditions "85
kv, 400 mA, 200 ms" corresponding to the above conditions from the
storage unit 14, and outputs these values to the emission
controller 5. These X-raying conditions are displayed on the
display unit 7 as shown in FIG. 3. Here, 85 kv is a tube voltage
value, 400 mA is a tube current value, and 200 ms is the X-ray
emission upper limit time.
[0069] [Step S3] Start X-Ray Radiography
[0070] A top board driving operation by the operator drives the top
board 1 to place the lower abdomen of the subject M between the
X-ray tube 2 and FPD 3. When a proper position is attained, in step
S3 the operator depresses the hand switch 8 to instruct a start of
X-ray radiography. The emission controller 5 controls the X-ray
tube 2 on these X-raying conditions "85 kv, 400 mA, 200 ms". That
is, the tube voltage controller 24 controls the tube voltage of the
X-ray tube 2 to "85 kv", the filament current controller 25
controls the tube current of the X-ray tube 2 to "400 mA", and the
radiographing time controller 26 controls the X-ray emission time
of the X-ray tube 2 for emission at the upper limit "200 ms".
[0071] [Step S4] Start Automatic Exposure Control
[0072] In step S4 the radiography controller 4 starts the automatic
exposure control in response to the instruction for starting X-ray
radiography given in step S3. That is, the automatic exposure
control by the automatic exposure controller 16 is started
simultaneously with start of X-ray emission, and the timer 18 of
the automatic exposure controller 16 starts measuring an actual
radiographing time.
[0073] [Step S5] Proper Amount of X Rays?
[0074] In step S5, the automatic exposure controller 16 determines,
based on the electric signals from the automatic exposure detector
13, whether a proper amount of X rays has been reached, and
controls to cut off the X-ray emission when the proper amount of X
rays has been reached. Of course, a first X-ray fluoroscopic image
(e.g. a mask image) has been acquired by the above cutoff time.
[0075] [Step S6] Store Actual Radiographing Time
[0076] In step S6, an actual radiographing time until the reaching
time in step S5 is stored in the storage unit 14. Supposing, for
example, the X-ray emission is cut off in "25 ms", since the timer
18 of the automatic exposure controller 16 clocks the X-ray
emission time from start of the X-ray emission, the time taken
until the time of X-ray emission cutoff ("25 ms" in this case) can
be obtained. This "25 ms" is displayed on the display unit 7 as
shown in FIG. 3.
[0077] [Step S7] Automatic Exposure Control OFF
[0078] In step S7, the radiography controller 4 turns off the
automatic exposure control of the automatic exposure controller 16,
and fixes the X-raying conditions to "85 kv, 400 mA, 25 ms". That
is, until cancellation of the depression of the hand switch 8 or
receipt of the operating instruction of the top board drive switch
9 described hereinafter, the radiography controller 4 controls
X-ray radiography to be carried out for the second and subsequent
images in the state of the automatic exposure control of the
automatic exposure controller 16 turned off and the X-raying
conditions fixed to "85 kv, 400 mA, 25 ms".
[0079] [Steps S8 and S9] Injection of Contrast Medium and
Acquisition of Live Images
[0080] The subject M is injected with a contrast medium in step S8,
and live images are acquired in step S9. That is, the operator
continues depressing the hand switch 8, and a sequential shooting
is being continued while the radiographic images of the subject M
do not move from the lower abdomen (in short, until receipt of an
instruction for driving the top board 1), in the state of the
automatic exposure control turned off and the X-raying conditions
fixed to "85 kv, 400 mA, 25 ms". Since the radiography can be
continued on the same conditions even when the contrast medium
flows in, radiographic images can be obtained in the same
background density.
[0081] It should be noted that, in Embodiment 1, the hand switch 8
remains depressed, and a sequential shooting is carried out, except
for a time when the top board drive switch 9 described hereinafter
is being depressed.
[0082] [Step S10] Change Site to Be Imaged to "Thigh"
[0083] Assume, for example, that the operator, having finished
acquiring live images of the lower abdomen in step S9 above, makes
a change to the next site to be imaged "thigh". In step S10, the
operator operates the top board drive switch 9 for driving the top
board 1 longitudinally to place a thigh of the subject M between
the X-ray tube 2 and FPD 3.
[0084] [Step S11] Start Automatic Exposure Control
[0085] After the top board driving operation by the operator is
finished and the driving of the top board 1 is completed to place
the thigh of the subject M between the X-ray tube 2 and FPD 3, in
step S11 the emission controller 5 controls the X-ray tube 2 on the
X-raying conditions "85 kv, 400 mA, 200 ms". The radiography
controller 4 starts the automatic exposure control in response to
completion of this top board driving. That is, the automatic
exposure control by the automatic exposure controller 16 is started
after completion of this top board driving, and the timer 18 of the
automatic exposure controller 16 starts measuring an actual
radiographing time.
[0086] [Step S12] Proper Amount of X Rays?
[0087] In step S12, the automatic exposure controller 16
determines, based on the electric signals from the automatic
exposure detector 13, whether a proper amount of X rays has been
reached, and controls to cut off the X-ray emission when the proper
amount of X rays has been reached. Of course, a first X-ray
fluoroscopic image (e.g. a mask image) has been acquired from the
resumption at the above cutoff time.
[0088] [Step S13] Store Actual Radiographing Time
[0089] In step S13, an actual radiographing time until the reaching
time in step S12 is stored in the storage unit 14. Supposing, for
example, the X-ray emission is cut off in "15 ms", since the timer
18 of the automatic exposure controller 16 clocks the X-ray
emission time from start of the X-ray emission, the time taken
until the time of X-ray emission cutoff ("15 ms" in this case) can
be obtained. This "15 ms" is displayed on the display unit 7.
[0090] [Step S14] Automatic Exposure Control OFF
[0091] In step S14, the radiography controller 4 turns off the
automatic exposure control of the automatic exposure controller 16,
and fixes the X-raying conditions to "85 kv, 400 mA, 15 ms". That
is, until cancellation of the depression of the hand switch 8 or
receipt of the operating instruction of the top board drive switch
9, the radiography controller 4 controls X-ray radiography to be
carried out for the second and subsequent images in the state of
the automatic exposure control of the automatic exposure controller
16 turned off and the X-raying conditions fixed to "85 kv, 400 mA,
15 ms".
[0092] [Steps S15 and S16] Injection of Contrast Medium and
Acquisition of Live Images
[0093] The subject M is injected with the contrast medium in step
S15, and live images are acquired in step S16. That is, the
operator continues depressing the hand switch 8, and a sequential
shooting is being continued while the radiographic images of the
subject M do not move from the lower abdomen (in short, until
receipt of an instruction for driving the top board 1), in the
state of the automatic exposure control turned off and the X-raying
conditions fixed to "85 kv, 400 mA, 15 ms". Since the radiography
can be continued on the same conditions even when the contrast
medium flows in, radiographic images can be obtained in the same
background density.
[0094] [Step S17] Change Site to Be Imaged to "Calf"
[0095] Assume, for example, that the operator, having finished
acquiring live images of the "thigh" in step S16 above, makes a
change to the next site to be imaged "calf". In step S17, the
operator operates the top board drive switch 9 for driving the top
board 1 longitudinally to place a calf of the subject M between the
X-ray tube 2 and FPD 3.
[0096] [Step S18] X-Ray Radiography with Automatic Exposure Control
and X-Raying Conditions Fixed
[0097] In step S18, as in steps S11-S16, X-ray radiography is
carried out with the automatic exposure control and X-raying
conditions fixed for the site to be imaged "calf".
[0098] [Step S19] Finish X-Ray Radiography
[0099] In step S19, the X-ray radiography is finished since the
series of X-ray photographing steps has been completed for the
lower abdomen, thigh and calf of the subject M.
[0100] As described above, the X-ray apparatus in Embodiment 1
includes the top board 1 for supporting a subject M, the X-ray tube
2 for emitting X rays toward the subject M on the top board 1, the
automatic exposure detector 13 opposed to the X-ray tube 2 across
the top board 1 for detecting X rays emitted from the X-ray tube 2
and transmitted through the subject M, the storage unit 14 for
storing X-raying conditions indicating conditions of X-ray emission
from the X-ray tube 2, the hand switch 8 for receiving X-ray
radiography start inputs, the top board drive switch 9 for
receiving instruction inputs for driving the top board 1, the drive
controller for performing drive control of the top board 1 based on
an instruction from this top board drive switch 9, the input
detector 15 for detecting a start instruction from the hand switch
8 or a drive instruction from the top board drive switch 9 during a
sequential shooting, the automatic exposure controller 16 for
starting, based on an input detection by the input detector 15,
X-ray emission from the X-ray tube 2 on X-raying conditions read
from the storage unit 14, and for stopping the X-ray emission from
the X-ray tube 2 when an amount of transmitted X rays detected by
the automatic exposure detector 13 reaches a predetermined value,
and the X-raying condition fixing controller 17 for carrying out
controls to cause an X-ray emission from the X-ray tube 2 on
X-raying conditions effective when the X-ray emission is stopped by
the automatic exposure controller 16, and turning off the automatic
exposure control by the automatic exposure controller 16, until a
next input is detected by the input detector 15. Thus, the
automatic exposure control can be carried out only at the time of
starting radiography, and a subsequent sequential shooting can be
carried out in the state of X-raying conditions at that time being
locked and the automatic exposure control being turned off.
Supposing an attempt is made to carry out X-ray radiography of a
new site to be imaged in place of a current site to be imaged,
since a drive instruction from the top board drive switch 9 (i.e.
instruction to drive the top board 1) is detected during the
sequential shooting, the automatic exposure control can be carried
out only at the time of starting radiography for the new site to be
imaged by this drive instruction, and a subsequent sequential
shooting can be carried out in the state of being locked to the
X-raying conditions effective at that time, with the automatic
exposure control turned off. As a result, a proper automatic
exposure control can be carried out without setting a radiographic
acquisition mode such as a subtraction mode, a mode of moving a
radiographic system or a fluoroscopic table, or a non-moving
mode.
[0101] At a time of sequential shooting for acquiring subtraction
images, for example, there is no need for setting a subtraction
mode, and a subsequent sequential shooting can be carried out in a
state of being locked to X-raying conditions acquired from the
automatic exposure control used only at the time of staring
radiography, and with the automatic exposure control turned off.
This allows a mask image and live images to be obtained on the same
X-raying conditions, thereby to obtain proper subtraction images
(difference images). Also in the case of an X-ray apparatus
combined with a digital processing device without a function of
notifying setting of the above mode, proper subtraction images
(difference images) can be obtained similarly. When X-ray
radiography is carried out for a plurality of sites as in leg DSA
(digital subtraction angiography), the automatic exposure control
is carried out once at the time of first radiography for the first
site to be imaged, the X-raying conditions at that time can be
locked, and X-ray radiography can be carried out on the locked
X-raying conditions until a change is made in the sites to be
imaged. When a shift is made to a different site to be imaged, by
moving the radiographic system or the fluoroscopic table, the
automatic exposure control is carried out once at the time of first
radiography for the different site to be imaged, and the X-raying
conditions at that time can be locked for X-ray radiography. Thus,
proper subtraction images (difference images) can be obtained also
when X-ray radiography is carried out for a plurality of sites.
[0102] Also when a sequential shooting is carried out to acquire
live images without moving the radiographic system and top board 1
(fluoroscopic table), there is no need for setting the conventional
"non-moving mode" or the like, and a subsequent sequential shooting
can be carried out in a state of being locked to X-raying
conditions acquired from the automatic exposure control used only
at the time of staring radiography, and with the automatic exposure
control turned off. This realizes a uniform luminance for all
frames of a series of live images, without being influenced by a
contrast medium such as barium.
[0103] That is, proper automatic exposure control can be carried
out without setting the radiographic acquisition mode.
[0104] X-raying conditions are never locked unconditionally. When
X-ray radiography is carried out for a plurality of sites, the
automatic exposure control function can be turned on only at the
time of starting radiography for each site to be imaged, thereby to
obtain proper radiographic images.
[0105] The X-raying conditions include a tube voltage value of the
X-ray tube 2, a tube current value of the X-ray tube 2 and an X-ray
emission time value of the X-ray tube 2. The automatic exposure
controller 16 has the timer 18 for measuring an actual
radiographing time after starting X-ray emission from the X-ray
tube 2 on the X-raying conditions read from the storage unit 14,
based on an input detection by the input detector 15, until the
amount of transmitted X rays detected by the automatic exposure
detector 13 reaches a predetermined value. The X-raying condition
fixing controller 17, until a next input is detected by the input
detector 15, fixes the actual radiographing time measured by the
timer 18 as X-ray emission time on the X-raying conditions, and
turns off the automatic exposure control by the automatic exposure
controller 16. Thus, the automatic exposure control can be carried
out only at the time of starting radiography, and a subsequent
sequential shooting can be carried out in the state of X-raying
conditions at that time (X-ray emission time of the X-ray tube 2
acquired by the automatic exposure control) being locked and the
automatic exposure control being turned off. Supposing an attempt
is made to carry out X-ray radiography of a new site to be imaged
in place of a current site to be imaged, since a drive instruction
from the drive instruction input device (i.e. instruction to drive
at least one of the X-ray emitting device and X-ray detecting
device, and the top board 1) is detected during the sequential
shooting, the automatic exposure control can be carried out only at
the time of starting radiography for the new site to be imaged by
this drive instruction, and a subsequent sequential shooting can be
carried out in the state of being locked to the X-raying conditions
effective at that time (X-ray emission time of the X-ray tube 2
acquired from the automatic exposure control), with the automatic
exposure control turned off. As a result, a proper automatic
exposure control can be carried out without setting a radiographic
acquisition mode such as a subtraction mode, a mode of moving a
radiographic system or a fluoroscopic table, or a non-moving
mode.
[0106] The storage unit 14 stores X-raying conditions indicating
conditions of X-ray emission from the X-ray tube 2, for each site
to be imaged. Thus, X-raying conditions can be stored for various
sites to be imaged, and various sites to be imaged can be X-rayed
conveniently.
[0107] This invention is not limited to the foregoing embodiment,
but may be modified as follows.
[0108] (1) The foregoing embodiment has been described,
exemplifying the radiographic system (X-ray tube 2 and FPD 3) being
fixed and the top board 1 being drivable. The invention is
applicable also where the top board 1 is fixed and the radiographic
system (X-ray tube 2 and FPD 3) is drivable. This can be realized
by the input detector 15 adapted to detect an operation input of a
drive switch which instructs driving of the radiographic
system.
[0109] (2) The foregoing embodiment has been described,
exemplifying the top board 1 for supporting a subject M. The
invention is applicable also where the top board is contactable by
the subject M (e.g. against which the subject M leans in a standing
position). In this case, the radiographic system (X-ray tube 2 and
FPD 3) may be constructed movable relative to the top board in an
upstanding state, longitudinally (in an upstanding direction) of
the top board. This can be realized by the input detector 15
adapted to detect an operation input of a drive switch which
instructs driving of the radiographic system.
[0110] (3) In the foregoing embodiment, the FPD 3 is employed for
detecting X rays transmitted through the subject M. However,
various detectors such as an I.I tube may be employed.
[0111] (4) The foregoing embodiment has been described,
exemplifying the hand switch 8 acting as the radiography start
instruction input device. A different type of hand switch may be
employed, which instructs an X-ray radiography start preparation
when a button portion of this hand switch is pushed in by one step,
and starts X-ray radiography when pushed in further. Instead of
being limited to hand switches, various controllers (input devices)
may be employed. The top board drive switch 9 is not limited to the
type in the embodiment, but various controllers (input devices) may
be employed.
[0112] (5) In the foregoing embodiment, the time when the amount of
transmitted X rays reaches a predetermined value in the automatic
exposure control is fixed as subsequent X-ray emission time.
Instead, the tube voltage and tube current may be monitored, and
values thereof may be fixed as subsequent X-raying conditions.
INDUSTRIAL UTILITY
[0113] As described above, this invention is suitable for X-ray
apparatus for medical and industrial uses.
* * * * *